// 是否为生产环境
const isProduction = process.env.NODE_ENV !== 'development'

// 本地环境是否需要使用cdn
const devNeedCdn = true

// cdn链接
const cdn = {
    // cdn：模块名称和模块作用域命名（对应window里面挂载的变量名称）
    externals: {
        vue: 'Vue',
        vuex: 'Vuex',
        vant: 'vant',
    },
    // cdn的css链接
    css: [],
    // cdn的js链接
    js: [
        'https://cdn.staticfile.org/vue/2.6.10/vue.runtime.min.js',
        'https://cdn.staticfile.org/vuex/3.1.2/vuex.min.js',
        'https://cdn.jsdelivr.net/npm/vant@2.2.15/lib/vant.min.js',

    ]
}


// 代码压缩
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
// gzip压缩
const CompressionWebpackPlugin = require('compression-webpack-plugin');

module.exports = {
    css: {
        loaderOptions: {
            postcss: {
                plugins: [
                    require('postcss-pxtorem')({ // 把px单位换算成rem单位
                        rootValue: 37.5, // 换算的基数(设计图750的根字体为32)
                        selectorBlackList: ['#app', '.px-', 'html', 'body'], // 忽略转换正则匹配的选择器
                        propList: ['*', '!border']
                    })
                ]
            }
        }
    },
    /**
     * 正式环境打包优化
     */
    productionSourceMap: false,
    chainWebpack: config => {
        // ============压缩图片 start============
        config.module
            .rule('images')
            .use('image-webpack-loader')
            .loader('image-webpack-loader')
            .options({bypassOnDebug: true})
            .end()
        // ============压缩图片 end============
        // ============注入cdn start============
        config.plugin('html').tap(args => {
            // 生产环境或本地需要cdn时，才注入cdn
            if (isProduction || devNeedCdn) args[0].cdn = cdn
            return args
        })
        // ============注入cdn start============
    },
    configureWebpack: config => {
        // 用cdn方式引入，则构建时要忽略相关资源
        if (isProduction || devNeedCdn) config.externals = cdn.externals;
        // 生产环境相关配置
        if (isProduction) {
            // 代码压缩
            config.plugins.push(
                new UglifyJsPlugin({
                    uglifyOptions: {
                        //生产环境自动删除console
                        compress: {
                            // warnings: false, // 若打包错误，则注释这行
                            drop_debugger: true,
                            drop_console: true,
                            pure_funcs: ['console.log']
                        }
                    },
                    sourceMap: false,
                    parallel: true
                })
            );
            // gzip压缩
            const productionGzipExtensions = ['html', 'js', 'css']
            config.plugins.push(
                new CompressionWebpackPlugin({
                    filename: '[path].gz[query]',
                    algorithm: 'gzip',
                    test: new RegExp(
                        '\\.(' + productionGzipExtensions.join('|') + ')$'
                    ),
                    threshold: 10240, // 只有大小大于该值的资源会被处理 10240
                    minRatio: 0.8, // 只有压缩率小于这个值的资源才会被处理
                    deleteOriginalAssets: false // 删除原文件
                })
            );
            // 公共代码抽离
            config.optimization = {
                splitChunks: {
                    cacheGroups: {
                        vendor: {
                            chunks: 'all',
                            test: /node_modules/,
                            name: 'vendor',
                            minChunks: 1,
                            maxInitialRequests: 5,
                            minSize: 0,
                            priority: 100
                        },
                        common: {
                            chunks: 'all',
                            test: /[\\/]src[\\/]js[\\/]/,
                            name: 'common',
                            minChunks: 2,
                            maxInitialRequests: 5,
                            minSize: 0,
                            priority: 60
                        },
                        styles: {
                            name: 'styles',
                            test: /\.(sa|sc|c)ss$/,
                            chunks: 'all',
                            enforce: true
                        },
                        runtimeChunk: {
                            name: 'manifest'
                        }
                    }
                }
            }
        }
    }
}
